A conventional mechanical seal device may have various problems caused by a sealed fluid when the mechanical seal device seals a clearance between rotating components of an apparatus which uses a chemical fluid, in particular, a refrigerant oil, a cooling medium, or the like. For example, in a case where a sealed fluid (working fluid) existing around a rotating shaft of a supply device (pump), a chemical device, or the like which supplies a refrigerant oil and an ammonia refrigerant is sealed, for example in a car air-conditioner, a refrigerator compression machine, or the like, there have been revealed various problems caused by a sealed fluid, such as a lack of a lubrication action on a sealing face of a mechanical seal. In particular, in a case where a sealed fluid such as a chemical fluid is sealed by a mechanical seal, a reaction substance or volatilized gas of the chemical fluid is generated between sliding sealing faces of a pair of sealing rings relatively sliding against each other and therefore heat may be generated due to sliding. In addition, a squeaking phenomenon between the sealing faces of the mechanical seal makes uncomfortable noises to the surrounding area. Furthermore, sealing performance of the sealing faces is deteriorated by the heat generated between the sliding sealing faces and therefore the sealed fluid may leak. Likewise, the sealing rings may be worn by the sealed fluid to be damaged thereby. These problems need to be urgently solved.
In such circumstance, there has been conventionally known a structure which is provided with a fluid introduction groove including: an opening which is formed in one of flat surfaces of sliding sealing faces of a pair of sealing rings relatively sliding against each other and which is opened to one of radially outward and inward sides; and an end portion which is located radially opposite to the opening so as to be in plane with the flat surface. The fluid introduction groove is configured to introduce a sealed fluid with lubricating property from the opening to the sliding sealing faces of the sealing rings relatively sliding against each other, thereby improving lubricity of the sealing faces (the structure will be hereinafter referred to as “a conventional technique”; for example, see Patent Citations 1 to 3).